The production of filaments, fibers, etc. from melamine/aldehyde polymers has been known for many years and patents and publications describing various innovations in this area of technology have continuously surfaced from time to time. U.S. Pat. No. 3,088,620 to Kuraray Co. Ltd. of Japan is exemplary of these publications. This patent teaches the production of flame-retardant, infusible fibers made from melamine/formaldehyde resins blended with a thermoplastic, fiber-forming polyvinyl alcohol resin having a degree of polymerization of from 500-3200 and a degree of saponification of 75-100 mole percent.
The melamine/formaldehyde resin used in said patent is produced by reaction of melamine and formaldehyde in the presence of a solvent at 50.degree.-900.degree. C. for 10 minutes to 3 hours. An acidic catalyst is usually employed and the resultant resin and the polyvinyl alcohol polymer are then blended before extrusion into a fiber. Alternatively, the melamine-formaldehyde reaction can be conducted in the presence of the polyvinyl alcohol polymer.
Spinning into a fiber is conducted by forming a spinning solution of the melamine/formaldehyde resinpolyvinyl alcohol polymer blend, ususally in water, extruding through a suitable spinnerette and then curing at 170.degree.-280.degree. C.
One of the problems which have plagued the melamine/formaldehyde resin fiber industry over the years is the inability to control the reaction of the melamine formaldehyde such as to obtain a resin have a narrow molecular species distribution. That is to say, when batch resin preparation techniques are employed, the resultant melamine/formaldehyde resin has a very wide molecular weight distribution which leads to variations in resin properties and characteristics. Additionally, reproducibility is very difficult. Attempts to reduce this scattering of molecular weights and non-reproducibility have not proven entirely satisfactory.
Additionally, when attempts are made to modify the melamine/formaldehyde resins with additives so as to impart particular fiber properties thereto, such as the use of polyvinyl alcohol polymers described above, these additives must have certain properties themselves so as to enable their use, i.e., primarily they must be soluble in the solvent media used for spinning, preferably water, or at least dispersible in the solvent-melamine resin solution, at the temperatures used for spinning. This requirement seriously reduces the number and variety of additives which have found utility in the industry over the past twenty years. If these two basic problems could be overcome, satisfaction of a long felt need in the art would be attained.